Known aqueous ink printing systems print images on substrates. Whether an image is printed directly onto a substrate or transferred from a blanket configured about an intermediate transfer member, once the image is on the substrate, the water and other solvents in the ink must be substantially removed from the surface to fix the image to the substrate. A dryer is typically positioned after the transfer of the image from the blanket or after the image has been printed on the substrate for removal of the water and solvents. To enable relatively high speed operation of the printer, the dryer uniformly heats the entire substrate and ink to temperatures that typically reach 100° C. and up to 140° C. in some cases. As the dried substrates move on the media transport path through the printer, they are cooled so they can be handled when they are discharged into the output tray.
One problem that arises during the drying of the aqueous ink images on substrates is the absorption of the water and other solvents into the substrates, particularly when the substrates are fibrous, such as paper. The absorption of the water and other solvents can wrinkle or otherwise distort the flatness of the substrates. Even after drying, the substrate can retain this uneven surface. As the substrates fill the output tray, this unevenness can present issues for stacking the printed substrates in the tray and the degree of unevenness in the surface of the substrates can impact the desirability of the printed sheets for the user. Being able to retain the original flatness of the substrates after the aqueous ink images on the substrates have been dried would be beneficial.